Process for making polysiloxane/polyimide copolymer blends

ABSTRACT

A method of making a thermoplastic composition comprises melt blending two polysiloxane/polyimide block copolymers. Both of the block copolymers have extended polysiloxane blocks.

CROSS REFERENCE TO RELATION APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/425,732 filed on Jun. 22, 2006 and which is incorporated byreference herein in its entirety.

BACKGROUND OF INVENTION

The disclosure relates to polysiloxane/polyimide block copolymers. Inparticular, the disclosure relates to polysiloxane/polyetherimide blockcopolymers.

Polysiloxane/polyimide block copolymers have been used due to theirflame resistance and high temperature stability. In some applications, agreater impact strength, particularly in combination with a low flexuralmodulus and a high tensile elongation is desirable. Accordingly, a needremains for polysiloxane/polyimide block copolymer compositions having adesired combination of low flammability, high temperature stability, lowflexural modulus, high tensile elongation, and high impact strength.

BRIEF DESCRIPTION OF THE INVENTION

A method of making a thermoplastic composition comprises melt blending:a first polysiloxane/polyimide block copolymer having a first siloxanecontent, based on the total weight of the first block copolymer, andcomprising repeating units of Formula (I)

a second polysiloxane/polyimide block copolymer having a second siloxanecontent, based on the total weight of the second block copolymer, andcomprising repeating units of Formula (I)

wherein R¹⁻⁶ are independently at each occurrence selected from thegroup consisting of substituted or unsubstituted, saturated, unsaturatedor aromatic monocyclic and polycyclic groups having 5 to 30 carbonatoms, substituted or unsubstituted alkyl groups having 1 to 30 carbonatoms and substituted or unsubstituted alkenyl groups having 2 to 30carbon atoms,V is a tetravalent linker selected from the group consisting ofsubstituted or unsubstituted, saturated, unsaturated or aromaticmonocyclic and polycyclic groups having 5 to 50 carbon atoms,substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms,substituted or unsubstituted alkenyl groups having 2 to 30 carbon atomsand combinations comprising at least one of the foregoing linkers,g equals 1 to 30, andd is greater than or equal to 1 andthe first siloxane content does not equal the second siloxane content.

A method of making a thermoplastic composition comprising melt blendinga first polysiloxane/polyimide block copolymer having a first siloxanecontent, based on the total weight of the first block copolymer, andcomprising repeating units of Formula (I)

a second polysiloxane/polyimide block copolymer having a second siloxanecontent, based on the total weight of the second block copolymer, andcomprising repeating units of Formula (I)

wherein R¹⁻⁶ are independently at each occurrence selected from thegroup consisting of substituted or unsubstituted, saturated, unsaturatedor aromatic monocyclic and polycyclic groups having 5 to 30 carbonatoms, substituted or unsubstituted alkyl groups having 1 to 30 carbonatoms and substituted or unsubstituted alkenyl groups having 2 to 30carbon atoms, V is a tetravalent linker selected from the groupconsisting of substituted or unsubstituted, saturated, unsaturated oraromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms,substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms,substituted or unsubstituted alkenyl groups having 2 to 30 carbon atomsand combinations comprising at least one of the foregoing linkers,

g equals 1 to 30, and

d is greater than or equal to 1 and

the first siloxane content equals the second siloxane content and thevalue of d for the first polysiloxane/polyimide block copolymer does notequal the value of d for the second polysiloxane/polyimide blockcopolymer.

Also described herein are reaction products produced by melt blendingtwo polysiloxane/polyimide block copolymers as described above as wellas articles comprising the thermoplastic composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a cross-section of conductivewire.

FIGS. 2 and 3 are perspective views of a conductive wire having multiplelayers.

FIGS. 4-6 are graphs of data from the Examples.

DETAILED DESCRIPTION

The terms “first,” “second,” and the like, “primary,” “secondary,” andthe like, as used herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.

The terms “a” and “an” do not denote a limitation of quantity, butrather denote the presence of at least one of the referenced item.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

The term “alkyl” is intended to include both C₁₋₃₀ branched andstraight-chain, unsaturated aliphatic hydrocarbon groups having thespecified number of carbon atoms. Examples of alkyl include but are notlimited to, methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl,t-butyl, n-pentyl, s-pentyl, n- and s-hexyl, n- and s-heptyl, and, n-and s-octyl.

The term “alkenyl” is defined as a C₂₋₃₀ branched or straight-chainunsaturated aliphatic hydrocarbon groups having one or more double bondsbetween two or more carbon atoms. Examples of alkenyl groups includeethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl andnonenyl and the corresponding C₂₋₁₀ dienes, trienes and quadenes.

The term “alkynyl” is defined as a C₂₋₁₀ branched or straight-chainunsaturated aliphatic hydrocarbon groups having one or more triple bondsbetween two or more carbon atoms. Examples of alkynes include ethynyl,propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, and nonynyl.

The term “substituted” means that one or more hydrogens on the molecule,portion of the molecule, or atom are replaced with substitution groupsprovided that an atom's normal valency is not exceeded, and that thesubstitution results in a stable compound. Such “substitution groups”may be selected from the group consisting of:, —OR, —NR′R, —C(O)R, —SR,-halo, —CN, —NO₂, —SO₂, phosphoryl, imino, thioester, carbocyclic, aryl,heteroaryl, alkyl, alkenyl, bicyclic and tricyclic groups. When asubstitution group is a keto (i.e., ═O) group, then 2 hydrogens on theatom are replaced. Keto substituents are not present on aromaticmoieties. The terms R and R′ refer to alkyl groups that may be the sameor different.

The description is intended to include all permutations and combinationsof the substitution groups on the backbone units specified by Formulas Iabove with the proviso that each permutation or combination can beselected by specifying the appropriate R or substitution groups.

Thus, for example, the term “substituted C₁₋₁₀ alkyl” refers to alkylmoieties containing saturated bonds and having one or more hydrogensreplaced by, for example, halogen, carbonyl, alkoxy, ester, ether,cyano, phosphoryl, imino, alkylthio, thioester, sulfonyl, nitro,heterocyclo, aryl, or heteroaryl.

The terms “halo” or “halogen” as used herein refer to fluoro, chloro,bromo, and iodo.

The term “monocyclic” as used herein refers to groups comprising asingle ring system. The ring system may be aromatic, heterocyclic,aromatic heterocyclic, a saturated cycloalkyl, or an unsaturatedcycloalkyl. The monocyclic group may be substituted or unsubstituted.Monocyclic alkyl groups may have 5 to 12 ring members.

The term “polycyclic” as used herein refers to groups comprisingmultiple ring systems. The rings may be fused or unfused. The polycyclicgroup may be aromatic, heterocyclic, aromatic heterocyclic, a saturatedcycloalkyl, an unsaturated cycloalkyl, or a combination of two or moreof the foregoing. The polycyclic group may be substituted orunsubstituted. Polycyclic groups may have 6 to 20 ring members.

The term “aryl” is intended to mean an aromatic moiety containing thespecified number of carbon atoms, such as, but not limited to phenyl,tropone, indanyl, or naphthyl.

The terms “cycloalkyl” are intended to mean any stable ring system,which may be saturated or partially unsaturated. Examples of suchinclude, but are not limited to, cyclopropyl, cyclopentyl, cyclohexyl,norbornyl, bicyclo[2.2.2]nonane, adamantyl, or tetrahydronaphthyl(tetralin).

As used herein, the term “heterocycle” or “heterocyclic system” isintended to mean a stable 5- to 7-membered monocyclic or 7- to10-membered bicyclic heterocyclic ring which is saturated, partiallyunsaturated, unsaturated or aromatic, and which consists of carbon atomsand 1 to 4 heteroatoms independently selected from the group consistingof N, O and S and including any bicyclic group in which any of theabove-defined heterocyclic rings is fused to a benzene ring. Thenitrogen and sulfur heteroatoms may optionally be oxidized. Theheterocyclic ring may be attached to its pendant group at any heteroatomor carbon atom that results in a stable structure. In this regard, anitrogen in the heterocycle may optionally be quaternized. When thetotal number of S and O atoms in the heterocycle exceeds 1, then theseheteroatoms are not adjacent to one another. In some embodiments thetotal number of S and O atoms in the heterocycle is not more than 1.

As used herein, the term “aromatic heterocyclic system” is intended tomean a stable 5- to 7-membered monocyclic or 7- to 10-membered bicyclicheterocyclic aromatic ring which consists of carbon atoms and from 1 to4 heteroatoms independently selected from the group consisting of N, Oand S. In some embodiments the total number of S and O atoms in thearomatic heterocycle is not more than 1.

Examples of heterocycles include, but are not limited to, 1H-indazole,2-pyrrolidonyl, 2H,6H-1,5,2-dithiazinyl, 2H-pyrrolyl, 3H-indolyl,4-piperidonyl, 4alphaH-carbazole, 4H-quinolizinyl,6H-1,2,5-thiadiazinyl, 5 acridinyl, azocinyl, benzimidazolyl,benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl,benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl,benzisothiazolyl, benzimidazalonyl, carbazolyl, 4alphaH-carbazolyl,beta-carbolinyl, chromanyl, chromenyl, cinnolinyl, decahydroquinolinyl,2H,6H-1,5,2-dithiazinyl, dihydrofuro[2,3-beta]tetrahydrofuran, furanyl,furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, 1H-indazolyl,indolenyl, indolinyl, indolizinyl, indolyl, isobenzofuranyl,isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl,isothiazolyl, isoxazolyl, morpholinyl, naphthyridinyl,octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl,1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl,oxazolyl, oxazolidinylperimidinyl, phenanthridinyl, phenanthrolinyl,phenarsazinyl, phenazinyl, phenothiazinyl, phenoxathiinyl, phenoxazinyl,phthalazinyl, piperazinyl, piperidinyl, pteridinyl, piperidonyl,4-piperidonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl,pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole,pyridothiazole, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl,pyrrolinyl, pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl,quinoxalinyl, quinuclidinyl, carbolinyl, tetrahydrofuranyl,tetrahydroisoquinolinyl, tetrahydroquinolinyl, 6H-1,2,5-thiadiazinyl,1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl,1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl,thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl,1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl,xanthenyl. Preferred heterocycles include, but are not limited to,pyridinyl, furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, indolyl,benzimidazolyl, 1H-indazolyl, oxazolidinyl, benzotriazolyl,benzisoxazolyl, oxindolyl, benzoxazolinyl, or isatinoyl. Also includedare fused ring and spiro compounds containing, for example, the aboveheterocycles.

The term “independently selected from”, “independently, at eachoccurance” or similar language, means that the labeled R substitutiongroups may appear more than once and may be the same or different whenappearing multiple times in the same structure. Thus the R¹ may be thesame or different than the R⁶ and if the labeled R⁶ substitution groupappears four times in a given permutation of Formula I, then each ofthose labeled R⁶ substitution groups may be, for example, a differentalkyl group falling within the definition of R⁶.

Polysiloxane/polyimide block copolymers comprise polysiloxane blocks andpolyimide blocks. In random polysiloxane/polyimide block copolymers thesize of the siloxane block is determined by the number of siloxy units(analogous to g in Formula (I)) in the monomer used to form the blockcopolymer. In some non-random polysiloxane/polyimide block copolymersthe order of the polyimide blocks and polysiloxane blocks is determinedbut the size of the siloxane block is still determined by the number ofsiloxy units in the monomer. In contrast, the polysiloxane/polyimideblock copolymers described herein have extended siloxane blocks. Two ormore siloxane monomers are linked together to form an extended siloxaneoligomer which is then used to form the block copolymer.Polysiloxane/polyimide block copolymers having extended siloxane blocksand a siloxane content of 5 weight percent to 30 weight percent, basedon the total weight of the block copolymer, have surprisingly highimpact strength.

Polysiloxane/polyimide block copolymers having extended siloxane blocksare made by forming an extended siloxane oligomer and then using theextended siloxane oligomer to make the block copolymer. The extendedsiloxane oligomer is made by reacting a diamino siloxane and adianhydride wherein either the diamino siloxane or the dianhydride ispresent in 10 to 50% molar excess, or, more specifically, 10 to 25%molar excess. “Molar excess” as used in this context is defined as beingin excess of the other reactant. For example, if the diamino siloxane ispresent in 10% molar excess then for 100 moles of dianhydride arepresent there are 110 moles of diamino siloxane.

Diamino siloxanes have Formula (II)

wherein R¹⁻⁶ and g are defined as above. In one embodiment R²⁻⁵ aremethyl groups and R¹ and R⁶ are alkylene groups. The synthesis ofdiamino siloxanes is known in the art and is taught, for example, inU.S. Pat. Nos. 3,185,719 and 4,808,686. In one embodiment R¹ and R⁶ arealkylene groups having 3 to 10 carbons. In some embodiments R¹ and R⁶are the same and in some embodiments R¹ and R⁶ are different.

Dianhydrides useful for forming the extended siloxane oligomer have theFormula (III)

wherein V is a tetravalent linker as described above. Suitablesubstitutions and/or linkers include, but are not limited to,carbocyclic groups, aryl groups, ethers, sulfones, sulfides amides,esters, and combinations comprising at least one of the foregoing.Exemplary linkers include, but are not limited to, tetravalent aromaticradicals of Formula (IV), such as:

wherein W is a divalent moiety such as —O—, —S—, —C(O)—, —SO₂—, —SO—,—C_(y)H_(2y)— (y being an integer of 1 to 20), and halogenatedderivatives thereof, including perfluoroalkylene groups, or a group ofthe Formula —O—Z—O— wherein the divalent bonds of the —O— or the —O—Z—O—group are in the 3,3′, 3,4′, 4,3′, or the 4,4′ positions, and wherein Zincludes, but is not limited to, divalent moieties of Formula (V).

wherein Q includes, but is not limited to, a divalent moiety comprising—O—, —S—, —C(O)—, —SO₂—, —SO—, —C_(y)H_(2y)— (y being an integer from 1to 20), and halogenated derivatives thereof, including perfluoroalkylenegroups. In some embodiments the tetravalent linker V is free ofhalogens.

In one embodiment, the dianhydride comprises an aromatic bis(etheranhydride). Examples of specific aromatic bis(ether anhydride)s aredisclosed, for example, in U.S. Pat. Nos. 3,972,902 and 4,455,410.Illustrative examples of aromatic bis(ether anhydride)s include:2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride;2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)diphenyl sulfone dianhydride;4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenyl-2,2-propanedianhydride; 4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenylether dianhydride;4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenyl sulfidedianhydride;4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)benzophenonedianhydride and4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenyl sulfonedianhydride, as well as mixtures comprising at least two of theforegoing.

The bis(ether anhydride)s can be prepared by the hydrolysis, followed bydehydration, of the reaction product of a nitro substituted phenyldinitrile with a metal salt of dihydric phenol compound in the presenceof a dipolar, aprotic solvent.

A chemical equivalent to a dianhydride may also be used. Examples ofdianhydride chemical equivalents include tetra-functional carboxylicacids capable of forming a dianhydride and ester or partial esterderivatives of the tetra functional carboxylic acids. Mixed anhydrideacids or anhydride esters may also be used as an equivalent to thedianhydride. As used throughout the specification and claims“dianhydride” will refer to dianhydrides and their chemical equivalents.

The diamino siloxane and dianhydride can be reacted in a suitablesolvent, such as a halogenated aromatic solvent, for exampleorthodichlorobenzene, optionally in the presence of a polymerizationcatalyst such as an alkali metal aryl phosphinate or alkali metal arylphosphonate, for example, sodium phenylphosphonate. In some instancesthe solvent will be an aprotic polar solvent with a molecular weightless than or equal to 500 to facilitate removal of the solvent from thepolymer. The temperature of the reaction can be greater than or equal to100° C. and the reaction may run under azeotropic conditions to removethe water formed by the reaction. In some embodiments thepolysiloxane/polyimide block copolymer has a residual solvent contentless than or equal to 500 parts by weight of solvent per million partsby weight of polymer (ppm), or, more specifically, less than or equal to250 ppm, or, even more specifically, less than or equal to 100 ppm.Residual solvent content may be determined by a number of methodsincluding, for example, gas chromatography.

The stoichiometric ratio of the diamino siloxane and dianhydride in thereaction to form the siloxane oligomer determines the degree of chainextension, (d in Formula (I)+1) in the extended siloxane oligomer. Forexample, a stoichiometric ratio of 4 diamino siloxane to 6 dianhydridewill yield a siloxane oligomer with a value for d+1 of 4. As understoodby one of ordinary skill in the art, d+1 is an average value for thesiloxane containing portion of the block copolymer and the value for d+1is generally rounded to the nearest whole number. For example a valuefor d+1 of 4 includes values of 3.5 to 4.5.

In some embodiments d is less than or equal to 50, or, morespecifically, less than or equal to 25, or, even more specifically, lessthan or equal to 10.

The extended siloxane oligomers described above are further reacted withnon-siloxane diamines and additional dianhydrides to make thepolysiloxane/polyimide block copolymer. The overall molar ratio of thetotal amount of dianhydride and diamine (the total of both the siloxaneand non-siloxane containing diamines) used to make thepolysiloxane/polyimide block copolymer should be about equal so that thecopolymer can polymerize to a high molecule weight. In some embodimentsthe ratio of total diamine to total dianhydride is 0.9 to 1.1, or, morespecifically 0.95 to 1.05. In some embodiments thepolysiloxane/polyimide block copolymer will have a number averagemolecular weight (Mn) of 5,000 to 50,000 Daltons, or, more specifically,10,000 to 30,000 Daltons. The additional dianhydride may be the same ordifferent from the dianhydride used to form the extended siloxaneoligomer.

The non-siloxane polyimide block comprises repeating units having thegeneral Formula (IX):

wherein a is more than 1, typically 10 to 1,000 or more, and canspecifically be 10 to 500; and wherein U is a tetravalent linker withoutlimitation, as long as the linker does not impede synthesis of thepolyimide oligomer. Suitable linkers include, but are not limited to:(a) substituted or unsubstituted, saturated, unsaturated or aromaticmonocyclic and polycyclic groups having 5 to 50 carbon atoms, (b)substituted or unsubstituted, linear or branched, saturated, orunsaturated alkyl groups having 1 to 30 carbon atoms; and combinationscomprising at least one of the foregoing linkers. Suitable substitutionsand/or linkers include, but are not limited to, carbocyclic groups, arylgroups, ethers, sulfones, sulfides amides, esters, and combinationscomprising at least one of the foregoing. Exemplary linkers include, butare not limited to, tetravalent aromatic radicals of Formula (IV), suchas:

wherein W is a divalent moiety such as —O—, —S—, —C(O)—, —SO₂—, —SO—,—C_(y)H_(2y)— (y being an integer of 1 to 20), and halogenatedderivatives thereof, including perfluoroalkylene groups, or a group ofthe Formula —O—Z—O— wherein the divalent bonds of the —O— or the —O—Z—O—group are in the 3,3′, 3,4′, 4,3′, or the 4,4′ positions, and wherein Zincludes, but is not limited to, divalent moieties of Formula (V).

wherein Q includes, but is not limited to, a divalent moiety comprising—O—, —S—, —C(O)—, —SO₂—, —SO—, —C_(y)H_(2y)— (y being an integer from 1to 20), and halogenated derivatives thereof, including perfluoroalkylenegroups. In some embodiments the tetravalent linker U is free ofhalogens.

In some embodiments V in the polysiloxane block and U in the polyimideblock are the same. In some embodiments V and U are different.

R¹⁰ in formula (IX) includes, but is not limited to, substituted orunsubstituted divalent organic moieties such as: aromatic hydrocarbonmoieties having 6 to 20 carbons and halogenated derivatives thereof;straight or branched chain alkylene moieties having 2 to 20 carbons;cycloalkylene moieties having 3 to 20 carbon atom; or divalent moietiesof the general formula (VIII)

wherein Q is defined as above. In some embodiments R⁹ and R¹⁰ are thesame and in some embodiments R⁹ and R¹⁰ are different.

In some embodiments the polysiloxane/polyimide block copolymer ishalogen free. Halogen free is defined as having a halogen content lessthan or equal to 1000 parts by weight of halogen per million parts byweight of block copolymer (ppm). The amount of halogen can be determinedby ordinary chemical analysis such as atomic absorption. Halogen freepolymers will further have combustion products with low smokecorrosivity, for example as determined by DIN 57472 part 813. In someembodiments smoke conductivity, as judged by the change in waterconductivity can be less than or equal to 1000 micro Siemens. In someembodiments the smoke has an acidity, as determined by pH, greater thanor equal to 5.

In one embodiment the non-siloxane polyimide blocks comprise apolyetherimide block. Polyetherimide blocks comprise repeating units ofFormula (X):

wherein T is —O— or a group of the Formula —O—Z—O— wherein the divalentbonds of the —O— or the —O—Z—O— group are in the 3,3′, 3,4′, 4,3′, orthe 4,4′ positions, and wherein Z and R¹⁰ are defined as describedabove.

The polyetherimide block can comprise structural units according toFormula (X) wherein each R¹⁰ is independently derived from p-phenylene,m-phenylene, diamino aryl sulfone or a mixture thereof and T is adivalent moiety of the Formula (XI):

Included among the many methods of making the polyimide oligomer,particularly polyetherimide oligomers, are those disclosed in U.S. Pat.Nos. 3,847,867; 3,850,885; 3,852,242; 3,855,178; 3,983,093; and4,443,591.

The repeating units of Formula (IX) and Formula (X) are formed by thereaction of a dianhydride and a diamine Dianhydrides useful for formingthe repeating units have the Formula (XII)

wherein U is as defined above. As mentioned above the term dianhydridesincludes chemical equivalents of dianhydrides.

In one embodiment, the dianhydride comprises an aromatic bis(etheranhydride). Examples of specific aromatic bis(ether anhydride)s aredisclosed, for example, in U.S. Pat. Nos. 3,972,902 and 4,455,410.Illustrative examples of aromatic bis(ether anhydride)s include:2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride;4,4′-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride;2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride;4,4′-bis(2,3-dicarboxyphenoxy)diphenyl sulfone dianhydride;4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenyl-2,2-propanedianhydride; 4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenylether dianhydride;4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenyl sulfidedianhydride;4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)benzophenonedianhydride and4-(2,3-dicarboxyphenoxy)-4′-(3,4-dicarboxyphenoxy)diphenyl sulfonedianhydride, as well as mixtures comprising at least two of theforegoing.

Diamines useful for forming the repeating units of Formula (IX) and (X)have the Formula (XIII)

H₂N—R¹⁰—NH₂  (XIII)

wherein R¹⁰ is as defined above. Examples of specific organic diaminesare disclosed, for example, in U.S. Pat. Nos. 3,972,902 and 4,455,410.Exemplary diamines include ethylenediamine, propylenediamine,trimethylenediamine, diethylenetriamine, triethylenetertramine,hexamethylenediamine, heptamethylenediamine, octamethylenediamine,nonamethylenediamine, decamethylenediamine, 1,12-dodecanediamine,1,18-octadecanediamine, 3-methylheptamethylenediamine,4,4-dimethylheptamethylenediamine, 4-methylnonamethylenediamine,5-methylnonamethylenediamine, 2,5-dimethylhexamethylenediamine,2,5-dimethylheptamethylenediamine, 2,2-dimethylpropylenediamine,N-methyl-bis(3-aminopropyl)amine, 3-methoxyhexamethylenediamine,1,2-bis(3-aminopropoxy)ethane, bis(3-aminopropyl) sulfide,1,4-cyclohexanediamine, bis-(4-aminocyclohexyl)methane,m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene,2,6-diaminotoluene, m-xylylenediamine, p-xylylenediamine,2-methyl-4,6-diethyl-1,3-phenylene-diamine,5-methyl-4,6-diethyl-1,3-phenylene-diamine, benzidine,3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 1,5-diaminonaphthalene,bis(4-aminophenyl)methane,bis(2-chloro-4-amino-3,5-diethylphenyl)methane, bis(4-aminophenyl)propane, 2,4-bis(p-amino-t-butyl) toluene,bis(p-amino-t-butylphenyl)ether, bis(p-methyl-o-aminophenyl)benzene,bis(p-methyl-o-aminopentyl)benzene, 1,3-diamino-4-isopropylbenzene,bis(4-aminophenyl) sulfide, bis(4-aminophenyl) sulfone,bis(4-aminophenyl)ether and 1,3-bis(3-aminopropyl)tetramethyldisiloxane. Mixtures of these compounds may also be used. Inone embodiment the diamine is an aromatic diamine, or, morespecifically, m-phenylenediamine, p-phenylenediamine, sulfonyl dianilineand mixtures thereof.

In general, the reactions can be carried out employing various solvents,e.g., o-dichlorobenzene, m-cresol/toluene, and the like, to effect areaction between the dianhydride of Formula (XII) and the diamine ofFormula (XIII), at temperatures of 100° C. to 250° C. Alternatively, thepolyimide block or polyetherimide block can be prepared by meltpolymerization or interfacial polymerization, e.g., melt polymerizationof an aromatic bis(ether anhydride) and a diamine by heating a mixtureof the starting materials to elevated temperatures with concurrentstirring. Generally, melt polymerizations employ temperatures of 200° C.to 400° C.

A chain-terminating agent may be employed to control the molecularweight of the polysiloxane/polyimide block copolymer. Mono-functionalamines such as aniline, or mono-functional anhydrides such as phthalicanhydride may be employed.

The polysiloxane/polyimide block copolymer may be made by first formingthe extended siloxane oligomer and then further reacting the extendedsiloxane oligomer with non-siloxane diamine and dianhydride.Alternatively a non-siloxane diamine and dianhydride may be reacted toform a polyimide oligomer. The polyimide oligomer and extended siloxaneoligomer can be reacted to form the polysiloxane/polyimide blockcopolymer.

When using a polyimide oligomer and an extended siloxane oligomer toform the block copolymer, the stoichiometric ratio of terminal anhydridefunctionalities to terminal amine functionalities is 0.90 to 1.10, or,more specifically, 0.95 to 1.05. In one embodiment the extended siloxaneoligomer is amine terminated and the non-siloxane polyimide oligomer isanhydride terminated. In another embodiment, the extended siloxaneoligomer is anhydride terminated and the non-siloxane polyimide oligomeris amine terminated. In another embodiment, the extended siloxaneoligomer and the non-siloxane polyimide oligomer are both amineterminated and they are both reacted with a sufficient amount ofdianhydride (as described above) to provide a copolymer of the desiredmolecular weight. In another embodiment, the extended siloxane oligomerand the non-siloxane polyimide oligomer are both anhydride terminatedand they are both reacted with a sufficient amount of diamine (asdescribed above) to provide a copolymer of the desired molecular weight.Reactions conditions for the polymerization of the siloxane andpolyimide oligomers are similar to those required for the formation ofthe oligomers themselves and can be determined without undueexperimentation by one of ordinary skill in the art.

The siloxane content in the block copolymer is determined by the amountof extended siloxane oligomer used during polymerization. The siloxanecontent can be 5 to 30 weight percent, or, more specifically, 10 to 25weight percent, based on the total weight of the block copolymer. Thesiloxane content is calculated using the molecular weight of the diaminosiloxane used to form the extended siloxane oligomer.

Polysiloxane/polyimide block copolymers having a siloxane content of 5to 30 weight percent, based on the total weight of the block copolymerand comprising repeating units of Formula (I) have a surprisingly highimpact strength when compared to comparable polysiloxane/polyimidecopolymers having a siloxane content greater than 30 weight percent andcomprising repeating units of Formula (I). The notched Izod strength atroom temperature can be greater than 267 Joules per meter (J/m), or,more specifically, greater than or equal to 374 J/m. In some embodimentsthe notched Izod is 267 to 1335 J/m (5 to 25 ft-lbf/in), or morespecifically, 374 J/m to 1068 J/m (7 to 20 ft-lbf/in). Notched Izodimpact can be determined by several methods known in the art, includingfor example ASTM D 256 using injection molded bars having a thickness of3.2 millimeters.

In one embodiment, the polysiloxane/polyimide block copolymer has asiloxane content of 5 to 30 weight percent, or, more specifically, 10 to25 weight percent, based on the total weight of the block copolymer andcomprises repeating units of Formula (I) wherein d+1 has a value of 3 to10, or, more specifically, 3 to 6.

In some embodiments, especially in demanding electronic applications,such as the fabrication of computer chips and the manipulation ofsilicone wafers, it is desirable to have polysiloxane/polyimide blockcopolymer or blend of polysiloxane/polyimide block copolymers with lowmetal ion content. In some embodiments the amount of metal ions is lessthan or equal to 1000 parts per million parts of copolymer (ppm), or,more specifically, less than or equal to 500 ppm or, even morespecifically, the metal ion content will be less than or equal to 100ppm. Alkali and alkaline earth metal ions are of particular concern. Insome embodiments the amount of alkali and alkaline earth metal ions isless than or equal to 1000 ppm in the high impact polysiloxane/polyimideblock copolymer and wires or cables made from them.

Two or more polysiloxane/polyimide block copolymers may be melt blendedto form a thermoplastic composition. The block copolymers may be used inany proportion. For example, when two block copolymers are used theweight ratio of the first block copolymer to the second block copolymermay be 1 to 99. Ternary blends and higher are also contemplated.

The thermoplastic composition may have a residual solvent content lessthan or equal to 500 parts by weight of solvent per million parts byweight of composition (ppm), or, more specifically, less than or equalto 250 ppm, or, even more specifically, less than or equal to 100 ppm.

In some embodiments the thermoplastic composition is halogen free.Halogen free is defined as having a halogen content less than or equalto 1000 parts by weight of halogen per million parts by weight ofthermoplastic composition (ppm). The amount of halogen can be determinedby ordinary chemical analysis such as atomic absorption. Halogen freethermoplastic compositions will further have combustion products withlow smoke corrosivity, for example as determined by DIN 57472 part 813.In some embodiments smoke conductivity, as judged by the change in waterconductivity can be less than or equal to 1000 micro Siemens. In someembodiments the smoke has an acidity, as determined by pH, greater thanor equal to 5.

In some embodiments the amount of metal ions in the thermoplasticcomposition is less than or equal to 1000 parts by weight of metal ionsper million parts by weight of thermoplastic composition (ppm), or, morespecifically, less than or equal to 500 ppm or, even more specifically,the metal ion content is less than or equal to 100 ppm. Alkali andalkaline earth metal ions are of particular concern. In some embodimentsthe amount of alkali and alkaline earth metal ions is less than or equalto 1000 ppm in the thermoplastic composition and wires or cables madefrom them.

In some embodiments the block copolymers used in the thermoplasticcomposition may have a degree of chain extension, d+1, of 3 to 10, or,more specifically, 3 to 6.

In some embodiments, a thermoplastic composition comprises a firstpolysiloxane/polyimide block copolymer having a first siloxane content,based on the total weight of the first block copolymer, and comprisingrepeating units of Formula (I); and a second polysiloxane/polyimideblock copolymer having a second siloxane content, based on the totalweight of the second block copolymer, and comprising repeating units ofFormula (I) wherein the first siloxane content does not equal the secondsiloxane content. By melt blending two or more polysiloxane/polyimideblock copolymers with different siloxane contents compositions withintermediate siloxane contents can be made predictably and reliably.Additionally, blending two block copolymers with different siloxanecontents yields compositions with unexpected impact strength.

In one embodiment a thermoplastic composition comprises twopolysiloxane/polyimide block copolymers both comprising repeating unitsof Formula (I). The polysiloxane/polyimide block copolymers havedifferent siloxane contents and different degrees of chain extension forthe polysiloxane block (d+1). In another embodiment a thermoplasticcomposition comprises two polysiloxane/polyimide block copolymers bothcomprising repeating units of Formula (I). The polysiloxane/polyimideblock copolymers have different siloxane contents but the same degree ofchain extension for the polysiloxane block (d+1).

In one embodiment, a thermoplastic composition comprises a firstpolysiloxane/polyimide block copolymer having a first siloxane content,based on the total weight of the first block copolymer, and comprisingrepeating units of Formula (I); and a second polysiloxane/polyimideblock copolymer having a second siloxane content, based on the totalweight of the second block copolymer, and comprising repeating units ofFormula (I) wherein the first siloxane content equals the secondsiloxane content and the value of d for the first polysiloxane/polyimideblock copolymer does not equal the value of d for the secondpolysiloxane/polyimide block copolymer. These blends are visually clear.

The blending of polysiloxane/polyimide block copolymer provides a usefulmethod to control the properties of the polysiloxane/polyimide blockcopolymer blend by, in some instances, attaining a property intermediateof the properties of the component polysiloxane/polyimide blockcopolymers. For example combining a high and low moduluspolysiloxane/polyimide block copolymers gives a blend of intermediatemodulus. In some embodiments copolymers of different molecular weightsmay be combined to produce a blend having a melt flow value needed insubsequent extrusion and molding operations. In terms of Izod impactsuch blends give surprisingly high impact strength.

The blends may further contain fillers and reinforcements for examplefiber glass, milled glass, glass beads, flake, and the like. Mineralssuch as talc, wollastonite, mica, kaolin or montmorillonite clay,silica, quartz, barite, and combinations of two or more of the foregoingmay be added. The compositions can comprise inorganic fillers, such as,for example, carbon fibers and nanotubes, metal fibers, metal powders,conductive carbon, and other additives including nano-scalereinforcements as well as combinations of inorganic fillers.

Other additives include, UV absorbers; stabilizers such as lightstabilizers and others; lubricants; plasticizers; pigments; dyes;colorants; anti-static agents; foaming agents; blowing agents; metaldeactivators, and combinations comprising one or more of the foregoingadditives. Antioxidants can be compounds such as phosphites,phosphonites and hindered phenols or mixtures thereof. Phosphoruscontaining stabilizers including triaryl phosphite and aryl phosphonatesare of note as useful additives. Difunctional phosphorus containingcompounds can also be employed. Stabilizers may have a molecular weightgreater than or equal to 300. In some embodiments, phosphorus containingstabilizers with a molecular weight greater than or equal to 500 areuseful. Phosphorus containing stabilizers are typically present in thecomposition at 0.05-0.5% by weight of the formulation. Flow aids andmold release compounds are also contemplated.

The thermoplastic composition can be prepared melt mixing or acombination of dry blending and melt mixing. Melt mixing can beperformed in single or twin screw type extruders or similar mixingdevices which can apply a shear and heat to the components. Melt mixingcan be performed at temperatures greater than or equal to the meltingtemperatures of the block copolymers and less than the degradationtemperatures of either of the block copolymers.

All of the ingredients may be added initially to the processing system.In some embodiments, the ingredients may be added sequentially orthrough the use of one or more master batches. It can be advantageous toapply a vacuum to the melt through one or more vent ports in theextruder to remove volatile impurities in the composition.

In one embodiment the composition comprises a reaction product of meltmixing the block copolymers.

In some embodiments melt mixing is performed using an extruder and thecomposition exits the extruder in a strand or multiple strands. Theshape of the strand is dependent upon the shape of the die used and hasno particular limitation.

In one embodiment, a conductive wire comprises a conductor and acovering disposed over the conductor. The covering comprises athermoplastic composition and the thermoplastic composition comprisestwo polysiloxane/polyimide block copolymers as described above. Thecomposition is applied to the conductor by a suitable method such asextrusion coating to form a conductive wire. For example, a coatingextruder equipped with a screw, crosshead, breaker plate, distributor,nipple, and die can be used. The melted thermoplastic composition formsa covering disposed over a circumference of the conductor. Extrusioncoating may employ a single taper die, a double taper die, otherappropriate die or combination of dies to position the conductorcentrally and avoid die lip build up.

In some embodiments it may be useful to dry the thermoplasticcomposition before extrusion coating. Exemplary drying conditions are 60to 90° C. for 2 to 20 hours. Additionally, in one embodiment, duringextrusion coating, the thermoplastic composition is melt filtered, priorto formation of the coating, through one or more filters. In someembodiments the thermoplastic composition will have substantially noparticles greater than 80 micrometers in size. In some embodiments anyparticulates present will be less than or equal to 40 micrometers insize. In some embodiments there will be substantially no particulatesgreater than 20 micrometers in size. The presence and size ofparticulates can be determined using a solution of 1 gram ofthermoplastic composition dissolved in 10 milliliters of a solvent, suchas chloroform, and analyzing it using microscopy or light scatteringtechniques. Substantially no particulates is defined as having less thanor equal to 3 particulates, or, more specifically, less than or equal to2 particulates, or, even more specifically, less than or equal to 1particulate per one gram sample. Low levels of particulates arebeneficial for giving a layer of insulation on a conductive wire thatwill not have electrically conductive defects as well as giving coatingswith improved mechanical properties, for instance elongation.

The extruder temperature during extrusion coating is generally less thanthe degradation temperature of the block copolymers. Additionally theprocessing temperature is adjusted to provide a sufficiently fluidmolten composition to afford a covering for the conductor, for example,higher than the softening point of the thermoplastic composition, ormore specifically at least 30° C. higher than the melting point of thethermoplastic composition.

After extrusion coating the conductive wire is usually cooled using awater bath, water spray, air jets, or a combination comprising one ormore of the foregoing cooling methods. Exemplary water bath temperaturesare 20 to 85° C.

In one embodiment, the composition is applied to the conductor to form acovering disposed over and in physical contact with the conductor.Additional layers may be applied to the covering. Methods of coating aconductor which may be used are well known in the art and are discussedfor example in U.S. Pat. No. 4,588,546 to Feil et al.; U.S. Pat. No.4,038,237 to Snyder et al.; U.S. Pat. No. 3,986,477 to Bigland et al.;and, U.S. Pat. No. 4,414,355 to Pokorny et al.

In one embodiment the composition is applied to a conductor having oneor more intervening layers between the conductor and the covering toform a covering disposed over the conductor. For instance, an optionaladhesion promoting layer may be disposed between the conductor andcovering. In another example the conductor may be coated with a metaldeactivator prior to applying the covering. Alternatively, a metaldeactivator can be mixed with the polysiloxane/polyimide blockcopolymers. In another example the intervening layer comprises athermoplastic or thermoset composition that, in some cases, is foamed.

The conductor may comprise a single strand or a plurality of strands. Insome cases, a plurality of strands may be bundled, twisted, braided, ora combination of the foregoing to form a conductor. Additionally, theconductor may have various shapes such as round or oblong. Suitableconductors include, but are not limited to, copper wire, aluminum wire,lead wire, and wires of alloys comprising one or more of the foregoingmetals. The conductor may also be coated with, e.g., tin, gold, orsilver. In some embodiments the conductor comprises optical fibers.

The cross-sectional area of the conductor and thickness of the coveringmay vary and is typically determined by the end use of the conductivewire. The conductive wire can be used as conductive wire withoutlimitation, including, for example, for harness wire for automobiles,wire for household electrical appliances, wire for electric power, wirefor instruments, wire for information communication, wire for electriccars, as well as ships, airplanes, and the like.

In some embodiments the covering may have a thickness of 0.01 to 10millimeters (mm) or, more specifically, 0.05 to 5 mm, or, even morespecifically 1 to 3 mm.

A cross-section of an exemplary conductive wire is seen in FIG. 1. FIG.1 shows a covering, 4, disposed over a conductor, 2. In one embodiment,the covering, 4, comprises a foamed thermoplastic composition.Perspective views of exemplary conductive wires are shown in FIGS. 2 and3. FIG. 2 shows a covering, 4, disposed over a conductor, 2, comprisinga plurality of strands and an optional additional layer, 6, disposedover the covering, 4, and the conductor, 2. In one embodiment, thecovering, 4, comprises a foamed thermoplastic composition. Conductor, 2,can also comprise a unitary conductor. FIG. 3 shows a covering, 4,disposed over a unitary conductor, 2, and an intervening layer, 6. Inone embodiment, the intervening layer, 6, comprises a foamedcomposition. Conductor, 2, can also comprise a plurality of strands.

Multiple conductive wires may be combined to form a cable. The cable maycomprise additional protective elements, structural elements, or acombination thereof. An exemplary protective element is a jacket whichsurrounds the group of conductive wires. The jacket and the covering onthe conductive wires, singly or in combination, may comprise thethermoplastic composition described herein. A structural element is atypically non conductive portion which provides additional stiffness,strength, shape retention capability or the like.

A color concentrate or master batch may be added to the compositionprior to or during extrusion coating. When a color concentrate is usedit is typically present in an amount less than or equal to 3 weightpercent, based on the total weight of the composition. In one embodimentthe master batch comprises a polysiloxane/polyimide block copolymer.

Further information is provided by the following non-limiting examples.

EXAMPLES Preparation of Polysiloxane/Polyimide Block Copolymer 1 (BC1)

Preparation of extended siloxane oligomer for BC1. A mixture of 1158liters (306 gallons) of o-dichlorobenzene (oDCB) was combined with 166kilograms (465 pounds) of bisphenol A dianhydride (BPADA) and 295kilograms (650 pounds) of a diamino propyl capped methyl siloxane having10 repeating siloxane units (G10) and 2 kilograms (4.7 pounds) phthalicanhydride. The G10 diamino siloxane had an average molecular weight ofabout 867. This mixture was heated with stirring to about 180° C. withthe removal of water.

The extended siloxane oligomer solution was then mixed with 204kilograms (449.8 pounds) of BPADA, 51 kilograms (112.1 pounds) ofm-phenylene diamine (mPD) and 2 kilograms (4.7 pounds) of phthalicanhydride which had been dissolved in 568 liters (150 gallons) of oDCB.The mixture was heated with removal of water until imidization wasessentially completed. The temperature was raised above 180° C. and mostof the oDCB solvent was distilled off The polymer mixture was thenpassed through two wiped film evaporators at 200 to 320° C. to reducethe oDCB content to below 500 ppm. The polymer was pumped from the wipedfilm evaporator through a die which formed it into continuous strands.The strands were cooled in a water bath and chopped into pellets. Mn was26,000 Daltons; weight average molecular weight (Mw) was 90,000 Daltonsas determined using gel permeation chromatography (GPC) as per ASTMmethod D5296. The melt flow rate at 295° C., using a 6.6 kilogramweight, was 27 grams/10 minutes.

Preparation of Polysiloxane/Polyimide Block Copolymer BC2

Preparation of extended siloxane oligomer. A mixture of 712 liters (188gallons) of oDCB was combined with 131 kilograms (289 pounds) of BPADAand 170 kilograms (374 pounds) of a diamino propyl capped methylsiloxane having 10 repeating siloxane units (G10) and 3.5 kilograms (7.8pounds) phthalic anhydride. The G10 diamino siloxane had an averagemolecular weight of about 897. This mixture was heated with stirring toabout 180° C. with the removal of water.

The extended siloxane oligomer solution was then mixed with 407kilograms (898 pounds) of BPADA, 93 kilograms (205 pounds) ofm-phenylene diamine (mPD) and 3.5 kilograms (7.8 pounds) of phthalicanhydride which had been dissolved in 1181 liters (312 gallons) of oDCB.The mixture was heated with removal of water until imidization wasessentially complete. The temperature was raised above 180° C. and mostof the oDCB was distilled off. The polymer mixture was then passedthrough two wiped film evaporators at 200 to 320° C. to reduce the oDCBcontent to below 500 ppm. The polymer was pumped from the wiped filmevaporator through a die which formed it into continuous strands. Thestrands were cooled in a water bath and chopped into pellets. Mn was14,600 Daltons; Mw was 44,000 Daltons as determined using gel permeationchromatography (GPC) as per ASTM method D5296. The melt flow rate at295° C., using a 6.6 kilogram weight, was 3.3 grams/10 minutes.

Preparation of Polysiloxane/Polyimide Block Copolymer BC3

Preparation of extended siloxane oligomer. A mixture of 848 liters (224gallons) of oDCB was combined with 227 kilograms (500 pounds) of BPADAand 140 kilograms (309 pounds) of a diamino propyl capped methylsiloxane having 10 repeating siloxane units (G10). The G10 diaminosiloxane had an average molecular weight of about 897. This mixture washeated with stirring to about 180° C. with the removal of water.

The extended siloxane oligomer solution was then mixed with 227kilograms (500 pounds) of BPADA, 78 kilograms (173 pounds) of mPD and5.6 kilograms (12.3 pounds) of phthalic anhydride which had beendissolved in 662 liters (175 gallons) of oDCB. This mixture was heatedwith removal of water until imidization was essentially complete. Thetemperature was raised above 180° C. and most of the oDCB solvent wasdistilled off The polymer mixture was then passed through two wiped filmevaporators at 200 to 320° C. to reduce the oDCB content to below 500ppm. The polymer was pumped from the wiped film evaporator through a diewhich formed it into continuous strands. The strands were cooled in awater bath and chopped into pellets. Mn was 14,500 Daltons; Mw was43,000 Daltons as determined using gel permeation chromatography (GPC)as per ASTM method D5296. The melt flow rate at 295° C., using a 6.6kilogram weight, was 7.1 grams/10 minutes.

In the following examples three polysiloxane/polyimide block copolymersas prepared above were used. All three block copolymers arepolysiloxane/polyetherimide block copolymers and were made usingextended siloxane oligomers. Details are provided in Table 1. Thesiloxane content includes total functionality of the diamino alkylsiloxane incorporated into the copolymer.

TABLE 1 Siloxane content Degree of chain extension (d + 1) BC 1 39.8weight percent 4 BC 2 22.9 weight percent 4 BC 3 21.6 weight percent 2

The polysiloxane/polyimide block copolymers and blends of the blockcopolymers were tested for glass transition temperature (Tg) bydifferential scanning calorimetry (DSC) in a nitrogen atmosphere;results are in ° C. Heat distortion temperature (HDT) was determined byASTM D 648 at 0.46 Megapascals (Mpa) (66 pounds per square inch (psi))and 1.82 MPa (264 psi) on 3 millimeter bars; results are in ° C. NotchedIzod was determined according to ASTM D 256 at 23° C. and at −20° C. on3 millimeter thick bars; results are reported in foot-pounds per inch(ft-lb/in) and Joules per meter (J/m). Tensile modulus and tensilestrength were determined according to ASTM D 638 on 3 millimeter thicktype I bars and results are reported in Kpsi and MPa. Tensile strengthis reported at yield. Flexural modulus and flexural strength weredetermined according to ASTM method D790 and results are reported inKpsi and MPa. Compositions and data are shown in Table 2. Amounts aregiven in weight percent based on the total weight of the composition.The blends were made by melt mixing in a vacuum vented twin screwextruder at 290 to 320° C. at 200 to 300 rotations per minute (rpm).Test parts were injection molded at 290 to 310° C. using a 30 secondcycle time from resin dried for at least 4 hours at 100 to 150° C. Allmolded samples were conditioned for at least 48 hours at 50% relativehumidity prior to testing.

TABLE 2 Siloxane Comp. content d + 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 1 Ex. 5Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 PS/PEI BC 3 22.9 2 100 75 50 25 —75 50 25 — — — — PS/PEI BC 2 21.6 4 — — — — — 25 50 75 100 25 50 75PS/PEI BC 1 39.8 4 — 25 50 75 100 — — — — 75 50 25 Appearance clearslight slight slight clear clear clear clear clear clear clear clearhaze haze haze Tg (° C.) 172 172 176 174 165 181 190 195 201 182 195 199HDT at 0.46 MPa 143 140 133 106 55 147 153 159 159 59 100 130 (° C.) HDTat 1.82 MPa 116 122 98 60 — 120 125 134 140 43 62 92 (° C.) Notched Izodat 1.6 8.2 9.0 7.5 5.4 3.4 6.2 7.0 18.0 5.4 9.9 15.4 25° C. (ft-lbs/in)Notched Izod at 85.4 437.9 480.6 400.5 288.4 181.6 331.1 373.8 961.2453.9 646.1 822.4 25° C. (J/m) Notched Izod at 1.2 5.4 7.0 6.3 4.2 2.23.5 3.8 4.6 8.5 12.1 12.1 −20° C. (ft-lbs/in) Notched Izod at 64.1 288.4373.8 336.4 224.3 117.5 186.9 202.9 246.6 240.3 528.7 646.1 −20° C.(J/m) Tensile Modulus 340 261 187 93 61 321 312 308 264 — — — (Kpsi)Tensile Modulus 2346 1801 1290 642 421 2215 2153 2125 1697 579 876 1347(MPa) Tensile Strength 10.3 8.3 6.2 4.1 3.0 9.9 9.7 9.6 6.8 — — — (Kpsi)Tensile Strength 71 57 43 28 21 68 67 66 47 25 30 35 (MPa) FlexuralModulus 345 269 206 124 52 323 317 305 203 — — — (Kpsi) Flexural Modulus2381 1856 1421 856 359 2229 2187 2105 1401 438 715 1027 (MPa) FlexuralStrength 16.7 12.8 9.6 5.4 1.9 15.5 15.2 14.6 9.9 — — — (Kpsi) FlexuralStrength 115 88 66 37 13 107 105 101 68 15.9 26.9 47.6 (MPa)

The room temperature notched Izod impact data from Table 2 is presentedgraphically in FIGS. 4, 5, and 6. FIG. 4 is a graph of the notched Izodimpact values of Examples 1 through 4 and Comparative Example 1 (CE 1).As can be seen from the graph, the impact strength of the blends(Examples 2 through 4) exceeds the impact strength of either ofindividual components (Example 1 and Comparative Example 1). Thus theblend of two polysiloxane/polyimide block copolymers results havingdiffering siloxane contents and degrees of polymerization yieldsthermoplastic compositions having surprising impact strength.

FIG. 5 is a graph of the room temperature notched Izod values ofExamples 8 through 11 and Comparative Example 1. Example 8, apolysiloxane/polyimide block copolymer having a siloxane content of 22.9wt % and a degree of chain extension of 4 demonstrates remarkably highimpact strength. Furthermore, blend of this polysiloxane/polyimide blockcopolymer with another polysiloxane/polyimide block copolymer having thesame degree of chain extension but a different siloxane content yields athermoplastic composition with remarkably high impact strength,particularly when compared to blends of block copolymers havingdifferent degrees of polymerization and the same siloxane content asshown in FIG. 6.

As an additional observation, only the blends of polysiloxane/polyimideblock copolymers with each other appear clear and have haze below 25% byvisual inspection. When any of the polysiloxane/polyimide blockcopolymers are blended with a non-siloxane containing polyetherimidesthe polymer blends are very hazy percent (haze >25% by visualinspection) or are opaque.

While the invention has been described with reference to someembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing fromessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiments disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety as though set forthin full.

1. A method of making a thermoplastic composition comprising meltblending a first polysiloxane/polyimide block copolymer having a firstsiloxane content, based on the total weight of the first blockcopolymer, and comprising a polysiloxane block and a non-siloxanepolyimide block wherein the polysiloxane block comprises repeating unitsof Formula (I)

and the polysiloxane block contains residues of reaction of a diaminosiloxane and a dianhydride wherein the reaction residue of diaminosiloxane is present in 10 to 50% molar excess; a secondpolysiloxane/polyimide block copolymer having a second siloxane content,based on the total weight of the second block copolymer, and comprisinga polysiloxane block and a non-siloxane polyimide block wherein thepolysiloxane block comprises repeating units of Formula (I)

and the polysiloxane block contains residues of reaction of a diaminosiloxane and a dianhydride wherein the reaction residue of diaminosiloxane is present in 10 to 50% molar excess; wherein R¹⁻⁶ areindependently at each occurrence selected from the group consisting ofsubstituted or unsubstituted, saturated, unsaturated or aromaticmonocyclic and polycyclic groups having 5 to 30 carbon atoms,substituted or unsubstituted alkyl groups having 1 to 30 carbon atomsand substituted or unsubstituted alkenyl groups having 2 to 30 carbonatoms, V is a tetravalent linker selected from the group consisting ofsubstituted or unsubstituted, saturated, unsaturated or aromaticmonocyclic and polycyclic groups having 5 to 50 carbon atoms,substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms,substituted or unsubstituted alkenyl groups having 2 to 30 carbon atomsand combinations comprising at least one of the foregoing linkers, gequals 1 to 30, and d is greater than or equal to 2 and the firstsiloxane content does not equal the second siloxane content.
 2. Themethod of claim 1 wherein the first polysiloxane/polyimide blockcopolymer has a value for d that does not equal the value for d of thesecond polysiloxane/polyimide block copolymer.
 3. The method of claim 1wherein the first polysiloxane/polyimide block copolymer has a value ford equal the value for d of the second polysiloxane/polyimide blockcopolymer.
 4. The method of claim 1 wherein R²⁻⁵ are methyl groups andR¹ and R⁶ are alkylene groups in the first block copolymer and R²⁻⁵ aremethyl groups and R¹ and R⁶ are alkylene groups in the second blockcopolymer.
 5. The method of claim 1 wherein the composition has aresidual solvent content less than or equal to 500 parts by weight ofsolvent per million parts by weight of block copolymer.
 6. The method ofclaim 1 wherein the siloxane content of the first block copolymer is 10to 25 weight percent based on the total weight of the first blockcopolymer and the siloxane content of the second block copolymer is 10to 25 weight percent based on the total weight of the second blockcopolymer.
 7. The method of claim 1 wherein the composition is halogenfree.
 8. The method of claim 1 wherein d+1 has a value of 3 to 6 in thefirst and second block copolymers.
 9. The method of claim 1 wherein theamount of alkali and alkaline earth metal ions in the first blockcopolymer and in the second block copolymer is less than or equal to1000 parts by weight per million parts by weight of block copolymer. 10.The reaction product of melt blending a first polysiloxane/polyimideblock copolymer having a first siloxane content, based on the totalweight of the first block copolymer, and comprising a polysiloxane blockand a non-siloxane polyimide block wherein the polysiloxane blockcomprises repeating units of Formula (I)

and the polysiloxane block contains residues of reaction of a diaminosiloxane and a dianhydride wherein the reaction residue of diaminosiloxane is present in 10 to 50% molar excess; a secondpolysiloxane/polyimide block copolymer having a second siloxane content,based on the total weight of the second block copolymer, and comprisinga polysiloxane block and a non-siloxane polyimide block wherein thepolysiloxane block comprises repeating units of Formula (I)

and the polysiloxane block contains residues of reaction of a diaminosiloxane and a dianhydride wherein the reaction residue of diaminosiloxane is present in 10 to 50% molar excess; wherein R¹⁻⁶ areindependently at each occurrence selected from the group consisting ofsubstituted or unsubstituted, saturated, unsaturated or aromaticmonocyclic and polycyclic groups having 5 to 30 carbon atoms,substituted or unsubstituted alkyl groups having 1 to 30 carbon atomsand substituted or unsubstituted alkenyl groups having 2 to 30 carbonatoms, V is a tetravalent linker selected from the group consisting ofsubstituted or unsubstituted, saturated, unsaturated or aromaticmonocyclic and polycyclic groups having 5 to 50 carbon atoms,substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms,substituted or unsubstituted alkenyl groups having 2 to 30 carbon atomsand combinations comprising at least one of the foregoing linkers, gequals 1 to 30, and d is greater than or equal to 2 and the firstsiloxane content does not equal the second siloxane content.